1. Field of the Invention
The present invention broadly relates to a reproducing apparatus having a rotary photosensitive drum or a developing drum supported by drum carriers and, more particularly, to a drive mechanism including a driving unit having a drive shaft adapted for driving each drum. Still more particularly, the invention is concerned with a mechanism for mounting the driving unit on the drum carrier.
2. Description of the Prior Art
In general, the axial alignment or misalignment between the driving rotary shaft for transmitting the driving power from a driving source such as motor and a rotary shaft which is driven by the driving rotary shaft largely affects the safe operation of the device which is operated by the rotary shaft, as well as the frequency of occurrence of troubles and, moreover, the durability of the device.
The connection between the driving rotary shaft and driven rotary shaft is usually achieved by means of a coupling. The axial alignment, which is generally referred to as "centering", is achieved by fitting the driven rotary shaft to the coupling fixed to the driving rotary shaft. Although the axial alignment is ensured to some extent by the fitting, the connection by the coupling does not always ensure the parallelism of axes of two shafts. Hitherto, the axial alignment and parallelism of two shafts have been attained by the centering work which is conducted by determining the position and inclination of the shaft within a three-dimensional space around the point of connection without any definite information concerning the amount and direction of error. Thus, the centering is quite inefficient work necessitating patience and time, although it is indispensable.
It is a common measure to employ a centering jig to avoid such inconveniences. The centering jig which is usable commonly for various centering works much have a play or tolerance in its size. An addition, the centering jig becomes unsatisfactory due to wear and deflection incurred during long common use. Therefore, hitherto, it has been necessary to prepare and carry independent centering jigs for various centering works.